The present invention relates to high-strength wear-resistant extruded aluminum alloy which excels in machinability during machining and caulking properties (or toughness).
The Japanese Industrial Standards define various types of aluminum alloy. A 4000 series alloy exhibits comparatively high wear resistance by adding Si to aluminum and causing hard Si particles to disperse and precipitate in the metallographic structure.
However, if a large number of hard Si particles exist in the metallographic structure, toughness of the metal material is decreased due to a notch effect originating from the Si particles.
The Si particles have the effect of dispersing chips during machining, but may cause the surface roughness of the machined surface to be decreased.
In the case of applying extruded aluminum alloy to automotive brake parts or the like, in addition to wear resistance against sliding parts, high machining accuracy and caulking accuracy are generally required.
In the case of manufacturing parts for an automotive antilock braking system actuator body (hereinafter called “ABS body”), a cylinder section including a piston and valve parts, a hydraulic circuit groove, and the like are subjected to machining, and a caulking seal or the like is provided after assembling the parts.
Therefore, not only the strength, but also wear resistance against sliding parts, machinability into a complicated shape, and pressure resistance of the caulking section against hydraulic oil or the like are required.
A further reduction in the size and weight of the ABS body has been demanded accompanying a reduction in the weight of automobiles. However, extruded aluminum alloy which can deal with such a demand has not been proposed.